scholarly journals Algorithm of DRM with Kinetic Damping for Finite Element Static Solution of Strain-Softening Structures

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Wei Wang ◽  
Xiaozu Su
Keyword(s):  
Finite Element ◽  
Static Analysis ◽  
Strain Softening ◽  
Computational Cost ◽  
Relaxation Method ◽  
Static Solution ◽  
Solution Procedure ◽  
Static Equilibrium ◽  
Equilibrium Path ◽  
Fe Model

In order to deal with the divergence and instability due to the ill-posedness of the nonlinear finite element (FE) model of strain-softening structure in implicit static analysis, the dynamic relaxation method (DRM) was used with kinetic damping to solve the static increments in the incremental solution procedure so that the problem becomes well-posed. Moreover, in DRM there is no need to assemble and inverse the stiffness matrix as in implicit static analysis such that the associated computational cost is avoided. The ascending branch of static equilibrium path was solved by load increments, while the peak point and the descending branch were solved by displacement increments. Two numerical examples illustrated the effectiveness of such application of DRM in the FE analysis of static equilibrium path of strain-softening structures.

The Effect of Trabecular Bone on the Mechanical Response of Human Mandible with Implant

2014 ◽  
Vol 695 ◽  
pp. 588-591
Author(s):  
Khairul Salleh Basaruddin ◽  
Ruslizam Daud
Keyword(s):  
Computed Tomography ◽  
Finite Element ◽  
Trabecular Bone ◽  
Static Analysis ◽  
Load Distribution ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Fe Model ◽  
Micro Computed Tomography ◽  
Bone Specimen

This study aims to investigate the influence of trabecular bone in human mandible bone on the mechanical response under implant load. Three dimensional voxel finite element (FE) model of mandible bone was reconstructed from micro-computed tomography (CT) images that were captured from bone specimen. Two FE models were developed where the first consists of cortical bone, trabecular bone and implants, and trabecular bone part was excluded in the second model. A static analysis was conducted on both models using commercial software Voxelcon. The results suggest that trabecular bone contributed to the strength of human mandible bone and to the effectiveness of load distribution under implant load.

scholarly journals Application of Artificial Neural Networks in Hybrid Simulation

2019 ◽  
Vol 9 (21) ◽  
pp. 4495 ◽  
Author(s):  
Mucha
Keyword(s):  
Finite Element ◽  
Real Time ◽  
Degrees Of Freedom ◽  
Computational Cost ◽  
Hybrid Simulation ◽  
Time Algorithm ◽  
High Accuracy ◽  
Small Time ◽  
Fe Model ◽  
Artificial Neural

Hybrid simulation is a technique for testing mechanical systems. It applies to structures with elements hard or impossible to model numerically. These elements are tested experimentally by straining them by means of actuators, while the rest of the system is simulated numerically using a finite element method (FEM). Data is interchanged between experiment and simulation. The simulation is performed in real-time in order to accurately recreate the dynamic behavior in the experiment. FEM is very computationally demanding, and for systems with a great number of degrees of freedom (DOFs), real-time simulation with small-time steps (ensuring high accuracy) may require powerful computing hardware or may even be impossible. The author proposed to swap the finite element (FE) model with an artificial neural network (ANN) to significantly lower the computational cost of the real-time algorithm. The presented examples proved that the computational cost could be reduced by at least one number of magnitude while maintaining high accuracy of the simulation; however, obtaining appropriate ANN was not trivial and might require many attempts.

A Computational Efficient Method to Assess the Sensitivity of Finite-Element Models: An Illustration With the Hemipelvis

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Dermot O'Rourke ◽  
Saulo Martelli ◽  
Murk Bottema ◽  
Mark Taylor
Keyword(s):  
Finite Element ◽  
Factorial Design ◽  
Surrogate Model ◽  
Computational Cost ◽  
Bone Geometry ◽  
Surrogate Models ◽  
Full Factorial Design ◽  
Fe Model ◽  
Kriging Surrogate Model ◽  
Full Factorial

Assessing the sensitivity of a finite-element (FE) model to uncertainties in geometric parameters and material properties is a fundamental step in understanding the reliability of model predictions. However, the computational cost of individual simulations and the large number of required models limits comprehensive quantification of model sensitivity. To quickly assess the sensitivity of an FE model, we built linear and Kriging surrogate models of an FE model of the intact hemipelvis. The percentage of the total sum of squares (%TSS) was used to determine the most influential input parameters and their possible interactions on the median, 95th percentile and maximum equivalent strains. We assessed the surrogate models by comparing their predictions to those of a full factorial design of FE simulations. The Kriging surrogate model accurately predicted all output metrics based on a training set of 30 analyses (R2 = 0.99). There was good agreement between the Kriging surrogate model and the full factorial design in determining the most influential input parameters and interactions. For the median, 95th percentile and maximum equivalent strain, the bone geometry (60%, 52%, and 76%, respectively) was the most influential input parameter. The interactions between bone geometry and cancellous bone modulus (13%) and bone geometry and cortical bone thickness (7%) were also influential terms on the output metrics. This study demonstrates a method with a low time and computational cost to quantify the sensitivity of an FE model. It can be applied to FE models in computational orthopaedic biomechanics in order to understand the reliability of predictions.

A Hybrid UKF-MAG Algorithm for Finite Element Model Updating of Historical Constructions

2019 ◽  
Author(s):  
Javier Naranjo-Pérez ◽  
Andrés Sáez ◽  
Javier F. Jiménez-Alonso ◽  
Pablo Pachón ◽  
Víctor Compán
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Kalman Filter ◽  
Finite Element Model ◽  
Unscented Kalman Filter ◽  
Computational Cost ◽  
Element Model ◽  
Fe Model ◽  
Multi Objective ◽  
Multi Objective Genetic Algorithm

<p>The finite element model (FE) updating is a calibration method that allows minimizing the discrepancies between the numerical and experimental modal parameters. As result, a more accurate FE model is obtained and the structural analysis can represent the real behaviour of the structure. However, it is a high computational cost process. To overcome this issue, alternative techniques have been developed. This study focuses on the use of the unscented Kalman filter (UKF), which is a local optimization algorithm based on statistical estimation of parameters taken into account the measurements. The dome of a real chapel is considered as benchmark structure. A FE model is updated applying two different algorithms: (i) the multi-objective genetic algorithm and (ii) a hybrid unscented Kalman filter-multi-objective genetic algorithm (UKF-MGA). Finally, a discussion of the results will be presented to compare the performance of both algorithms.</p>

A Comparative Study on the Beam and Continuum Finite Element Models for the Rail–Wheel Vibration

2019 ◽  
Vol 19 (07) ◽  
pp. 1950076 ◽  
Author(s):  
Q. Xie ◽  
Y. X. Zhou ◽  
Y. Zhan ◽  
K. Y. Sze ◽  
W. S. Han
Keyword(s):  
Finite Element ◽  
Numerical Models ◽  
Computational Cost ◽  
Field Tests ◽  
Maintenance Cost ◽  
Fe Model ◽  
Beam Model ◽  
Rolling Wheel ◽  
Wheel Vibration ◽  
Plane Continuum

The rail–wheel interaction can induce train and track vibrations and consequently lead to noise impact, passengers’ discomfort, high maintenance cost, etc. Due to the complexity of the rail–wheel interaction and the high cost of field tests, as well as the difficulties in data collection, numerical analyses have been widely resorted to for predicting the train and track vibrations, for which numerous numerical models have been developed. According to track modeling approaches, numerical models can be generally divided into two categories, i.e. beam models and continuum finite element (FE) models. In this paper, these two models are systematically compared and discussed. First, a typical beam model of Wu and Thompson [T. X. Wu and D. Thompson, On the parametric excitation of the wheel/track system, J. Sound Vib. 278(4) (2004) 725–747.] is introduced, based on which a modified model is then established. Secondly, a plane continuum FE model with high mesh quality is established, in which the transition mesh generation, contact treatment and element size determination are presented. Numerical tests are conducted to validate the proposed plane FE model. Finally, both the beam and the plane continuum FE models are examined through typical rail–wheel interaction examples, in which the linear response of the track as well as the rail–wheel vibrations under both a single rolling wheel and two rolling wheels are analyzed. The results show that most of the vibration trends obtained from the two models agree well with each other. Nevertheless, it is noteworthy that the continuum FE model has superiorities, especially for analyzing vibrations at higher frequencies. The present study can be of considerable help for designers and engineers in the railway industry to achieve the trade-off between the simulation demands and the computational cost.

Improvement on the Analysis of a Finite Element Composites Model

2013 ◽  
Author(s):  
Atanas A. Atanasov ◽  
Thomas J. Wright ◽  
John P. Parmigiani
Keyword(s):  
Finite Element ◽  
Computational Cost ◽  
Stress And Strain ◽  
Finite Element Models ◽  
Fe Model ◽  
Computational Costs ◽  
Composite Models ◽  
Experimental Values ◽  
Abaqus Model ◽  
Abaqus Software

Finite element models are increasingly being utilized in composite materials design; thus, an increase in the accuracy of the model analysis and a decrease in computational cost are of paramount importance. This study investigates the effects of a particular add-on, Helius:MCT (Firehole Technologies, Inc.), onto the Abaqus (Dassault Systèmes) software package. Unlike the stand-alone Abaqus software, Helius:MCT embodies a solver, which analyzes the composite structure by separating the fiber and matrix into constituent parts. Treating the fiber and matrix as separate, yet linked entities, allows for a more accurate depiction of the formations of stress and strain within the composite. Furthermore, Helius:MCT utilizes a method called Intelligent Discrete Softening (IDS), a feature not present within Abaqus, to increase solver robustness and convergence probability. An Abaqus finite element (FE) model of a notched, carbon-fiber panel loaded in bending was used in this study. Six different laminate combinations were tested with six variations of the Abaqus model. Three of the variations used Helius:MCT with Abaqus and three the stand-alone Abaqus package. The combinations were composed of either 20 or 40 plies with 10, 30, or 50 percent all zero ply orientations. All the FE analysis results were compared to experimental values for a plate of the exact configuration as that of the model. The most accurate results were obtained using Helius:MCT. The configuration with the greatest accuracy utilizes Helius:MCT and deviates an average of 1.7 percent from experimental values for maximum flexural strength. A single run takes an average of 7 hours to complete. Conversely, the most accurate configuration obtained without the use of Helius:MCT deviates an average of 10 percent from the experimental values and takes over 80 hours to run. Helius: MCT increases the accuracy and decreases the computational costs of the analyses of composite models in Abaqus. The improvements in analyses while using Helius: MCT may allow for a substantial savings in experimental costs and in valuable time.

A Tetraparametric Metamodel for the Analysis and Design of Bolting Sequences for Wind Generator Flanges

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Mikel Abasolo ◽  
Josu Aguirrebeitia ◽  
Rafael Avilés ◽  
Igor Fernández de Bustos
Keyword(s):  
Finite Element ◽  
Computational Cost ◽  
Elastic Interaction ◽  
Bolted Joints ◽  
Experimental Measurements ◽  
Fe Model ◽  
Analysis And Design ◽  
Linear Elastic ◽  
Wind Generator ◽  
Contact Surfaces

This paper presents a metamodel that enables estimation of the elastic interaction that occurs in the bolted joints of a wind generator tower during the tightening sequence. In this kind of joint, there is a gap between the contact surfaces of the flanges. The metamodel is composed of four parameters, which are enough to simulate the response of the flange under the tightening loads of the bolts. Even though the behavior of the joint is nonlinear because of the gap, the parameters are obtained from two simple linear elastic analyses of a finite element (FE) model of the flange. The corresponding loss of load in the bolts has been estimated for various sequences with minimum computational cost. Thus, there is no need for costly experimental measurements or nonlinear FE simulations.

COUPLED BOUNDARY ELEMENT-FINITE ELEMENT MODEL TO ESTIMATE HUMAN HEEL-PAD ELASTICITY MODULUS

2017 ◽  
Vol 29 (03) ◽  
pp. 1750018
Author(s):  
Amirhossein Salimi ◽  
Hamid-Reza Katouzian ◽  
Paniz Naraghi-Bagherpour ◽  
Mohammad-Mehdi Khani
Keyword(s):  
Finite Element ◽  
Boundary Element ◽  
Computational Cost ◽  
Element Model ◽  
Elastic Behavior ◽  
Fe Model ◽  
Heel Pad ◽  
Local Stresses ◽  
Indentation Experiment

The key role of heel-pad in protecting calcaneus bone against excessive local stresses during walking and running is well discussed in the literature. Aiming to obtain a more profound understanding of this soft collagenous load-bearing tissue, material characterization of heel-pad has attracted the attention of many researchers. One way of achieving this goal is to estimate the mechanical properties of heel-pad based on Finite Element (FE) simulation of the indentation experiment which has been conducted by various teams before. During this process, the soft tissue undergoes a relatively large deformation causing the elements in FE Model to be extremely distorted particularly near the vicinity of indenter-heel pad contact making the numerical modeling tedious and significantly increasing the computational cost. The main contribution of the current study is to develop a coupled Boundary Element–Finite Element (BE–FE) plane strain model to improve the deficiency of the conventional numerical methods as the three-node 1 degree-of-freedom BEs eliminate the distortion issue near the deformed heel-pad zone and effectively lower the computational costs which is vital for iterative processes of this kind. Later through iterative post-processing of data, the modulus of elasticity (E) describing the elastic behavior of heel-pad is extracted. E is determined by using the inverse technique to minimize the displacement error between the experimental data and the corresponding numerical results after a considerable number of iterations. Obtained results contribute in design and construction of state-of-the-art prosthetic feet and therapeutic foot wear.

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

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